Evaluation of Synovitis of Hand in Patients With Rheumatoid Arthritis Using Diffusion Kurtosis Magnetic Resonance Imaging: Initial Findings.

OBJECTIVE To explore the role of diffusion kurtosis magnetic resonance (MR) imaging in the noninvasive identification of synovitis in hand arthritis. METHODS A total of 30 patients with rheumatoid arthritis (RA) and 10 patients suspected of RA were enrolled in the prospective study. A 3.0-T MR imaging including the diffusion kurtosis MR imaging sequence (b = 0, 500, 1000, 1500, 2000 s·mm2) was performed. A total of 210 regions of interest were confirmed and diffusion kurtosis MR imaging parameters were generated. The suspected synovitis or effusion was scored on a scale of 0 (effusion) to 3 (mild, moderate, severe synovitis), according to RA-MR imaging scoring system. The performance of diffusion kurtosis MR imaging parameters (the apparent diffusion coefficient [ADC], diffusion coefficient [D], and kurtosis [K]) in distinguishing different synovitis scores was evaluated. RESULTS There were significant differences in ADC, D, and K values among different synovitis scores (all P < 0.001). Synovitis scores were negatively correlated with the ADC and D values significantly (r = -0.725, -0.757, respectively, all P < 0.001), but positively correlated with the K values significantly (r = 0.429, P < 0.001). The area under the curve values of D, ADC, and K values were 0.884, 0.874, and 0.728 for differentiating score 1-3 from score 0, respectively. Diffusion coefficient and ADC had similar diagnostic performance, and both were higher than K in detecting synovitis. No significant difference was found between the ADC and D values in detecting synovitis. CONCLUSIONS The diffusion kurtosis MR imaging may be feasible as a noninvasive method for the diagnosis and grading of synovitis in the hands of RA patients, and the D and ADC values showed similar diagnostic performance, both of which were higher than K values.